The DNA sequence of the human X chromosome

The human X chromosome has a unique biology that was shaped by its evolution as the sex chromosome shared by males and females. We have determined 99.3% of the euchromatic sequence of the X chromosome. Our analysis illustrates the autosomal origin of the mammalian sex chromosomes, the stepwise process that led to the progressive loss of recombination between X and Y, and the extent of subsequent degradation of the Y chromosome. LINE1 repeat elements cover one-third of the X chromosome, with a distribution that is consistent with their proposed role as way stations in the process of X-chromosome inactivation. We found 1,098 genes in the sequence, of which 99 encode proteins expressed in testis and in various tumour types. A disproportionately high number of mendelian diseases are documented for the X chromosome. Of this number, 168 have been explained by mutations in 113 X-linked genes, which in many cases were characterized with the aid of the DNA sequence.

Maintenance of mouth hygiene in patients with oral cancer in the immediate post-operative period

BACKGROUND

Little has been written about mouth hygiene measures during the immediate postoperative phase in patients with oral cancer. Mouth hygiene not only involves the care and maintenance of the dentition and its related structures, but also the maintenance of surgical sites, reconstructive techniques such as free flaps and generally keeping the mouth clean, which may optimize healing potential and patient comfort. Ward conditions and novel methods of reconstruction require innovation and improvisation of routine methods of mouth and oral hygiene.

METHODS

A review of techniques of mouth hygiene used during the immediate post-operative phase by our unit over the last nine years and a review of the literature.

RESULTS

Various methods gained from our experience in treating patients with oral cancer at the Austin and Repatriation Medical Centre are documented. Most methods involve a combination of either chlorhexidine or normal saline mouth rinses and mechanical cleaning.

CONCLUSIONS

There are many different methods of mouth care in patients who have had resection for oral tumours. It is important for dental practitioners, hygienists and allied health professionals, who may be involved with care of such patients to have an understanding of the methods that are available and appropriate for such patients.

Reconstructive techniques for the repair of oral and maxillofacial oncological procedures: what are they, how do they work and what do they look like?

BACKGROUND

There are many different ways to reconstruct the oral and maxillofacial region post tumour ablation. In the past, the resection of oral tumours had been associated with significant disfigurement and loss of function. Modern techniques aim to restore function and improve cosmetics. This paper aims to describe the techniques used in patients treated at the Austin and Repatriation Medical Centre and to answer the more common questions associated with reconstructive techniques.

METHODS

A review of techniques of oral reconstruction used by our unit over the last nine years and a review of the literature.

RESULTS

Various techniques of reconstruction gained from our experience in treating patients with oral cancer are documented. There are a variety of techniques including grafts, local flaps, regional flaps and free vascularized flaps. Metallic implants such as osseointegrated dental implants may also be used for dental rehabilitation.

CONCLUSIONS

There are many different methods of reconstruction in patients who have had resection for oral tumours. It is important for general dental practitioners who may be involved with the care of such patients to have an understanding of the modern techniques of reconstruction that may be used.

The DNA sequence and comparative analysis of human chromosome 20

The finished sequence of human chromosome 20 comprises 59,187,298 base pairs (bp) and represents 99.4% of the euchromatic DNA. A single contig of 26 megabases (Mb) spans the entire short arm, and five contigs separated by gaps totalling 320 kb span the long arm of this metacentric chromosome. An additional 234,339 bp of sequence has been determined within the pericentromeric region of the long arm. We annotated 727 genes and 168 pseudogenes in the sequence. About 64% of these genes have a 5' and a 3' untranslated region and a complete open reading frame. Comparative analysis of the sequence of chromosome 20 to whole-genome shotgun-sequence data of two other vertebrates, the mouse Mus musculus and the puffer fish Tetraodon nigroviridis, provides an independent measure of the efficiency of gene annotation, and indicates that this analysis may account for more than 95% of all coding exons and almost all genes.

Treatment planning for the problem patient: restorative, ethical, legal and psychological perspectives. Case 4: Mr Lester

'Mr Lester' is the final case study in a series of four articles that aims to look at some of the problems patients may present with when they visit their dentist. Each article starts with a brief scenario about the hypothetical patient and his/her clinical problems. As well as the clinical problem, each case also raises ethical, legal or psychological problems. All of these issues are discussed and possible management strategies and treatment options investigated.

Treatment planning for the problem patient: restorative, ethical, legal and psychological perspectives. Case 3: Mary

Mary' is the third of a series of four articles that aims to look at some of the problems patients may present with when they visit their dentist. Each article starts with a brief scenario about the hypothetical patient and his/her clinical problems. As well as the clinical problem, each case also raises ethical, legal or psychological problems. All of these issues are discussed and possible management strategies and treatment options investigated.

Treatment planning for the problem patient: restorative, ethical, legal and psychological perspectives. Case 2: Jacqueline

Jacqueline's is the second of a series of four articles that aims to look at some of the problems patients may present with when they visit their dentist. Each article starts with a brief scenario about the hypothetical patient and his/her clinical problems. As well as the clinical problem, each case also raises ethical, legal or psychological problems. All of these issues are discussed and possible management strategies and treatment options described.

Treatment planning for the problem patient: restorative, ethical, legal and psychological perspectives. Case I: Emma

'Emma' is the first of a series of four articles that aims to look at some of the problems patients may present with when they visit their dentist. Each article starts with a brief scenario about the hypothetical patient and his/her clinical problems. As well as the clinical problem, each case also raises ethical, legal or psychological problems. All of these issues are discussed and possible management strategies and treatment options described.

Midfacial tumours: a review of 72 cases

We review 72 midfacial tumours managed during the 10-year period between 1985 and 1995. We describe presenting features, sites of lesions and histology, treatment regimens and outcomes, as well as the various surgical approaches for the resection of midfacial tumours, and their indications and contraindications. The choice of approach should be based on type of tumour, its site, and extent.

The DNA sequence of human chromosome 22

Knowledge of the complete genomic DNA sequence of an organism allows a systematic approach to defining its genetic components. The genomic sequence provides access to the complete structures of all genes, including those without known function, their control elements, and, by inference, the proteins they encode, as well as all other biologically important sequences. Furthermore, the sequence is a rich and permanent source of information for the design of further biological studies of the organism and for the study of evolution through cross-species sequence comparison. The power of this approach has been amply demonstrated by the determination of the sequences of a number of microbial and model organisms. The next step is to obtain the complete sequence of the entire human genome. Here we report the sequence of the euchromatic part of human chromosome 22. The sequence obtained consists of 12 contiguous segments spanning 33.4 megabases, contains at least 545 genes and 134 pseudogenes, and provides the first view of the complex chromosomal landscapes that will be found in the rest of the genome.

Iatrogenic bismuth poisoning. Case report

A case of bismuth intoxication following the intraoral use of BIPP-impregnated gauze packs is presented. This report illustrates the need for caution when using potentially toxic compounds in the oral cavity where significant quantities can be absorbed to produce symptoms of poisoning.